巨磁阻模型中热产生分布的理论研究

Theory of the Heat Generation in Giant Magnetoresistance Model

摘要: 自旋热效应是最近出现的研究领域，内容围绕于自旋与热流的相互作用，引起了广泛的讨论。由于热效应对纳米尺度的电子器件的电学、热学和磁学性能的研究有重要的意义，磁性多层结构中存在的热产生是一个不容忽视的问题。我们用基于玻尔兹曼方程的宏观近似，在理论上研究了磁性多层结构中由于输运导致热产生。在磁性多层结构中通入电流后，除了会产生普通材料的焦耳热外，还存在来自于自旋积累的额外热产生。我们用巨磁阻模型计算了热产生分布的表达式，并比较了反平行结构和平行结构中自旋相关热产生分布和大小的差异。分析结果表明，在反平行结构中，自旋相关热产生比较多，对材料的影响比较大，而平行结构中自旋相关热产生比较少。所以，当两个铁磁层磁化方向变化时，装置中的热产生也发生明显的变化，是一种类巨磁阻效应。

Abstract: Spin caloritronics is a newly-explored research field concerning mainly the interaction of spin and heat, and has attracted extensive research interests recently. Heat generation in magnetic multilayers is a serious problem, because it has significant effects on the electric, thermal, and magnetic properties of nanoscale electronic devices. Here we study theoretically the heat generation due to spin transport in magnetic multilayers by using a macroscopic approach based on the Boltzmann equation. There exists extra heat generation due to spin accumulation besides the nominal Joule heat, when a current flows through the magnetic multilayers. On the basis of the giant magnetoresistance (GMR) model, we derived the expressions for the distribution of heat generation. We also compared the distribution and magnitude of the heat generation in an-tiparallel (AP) and parallel (P) alignments. Our analysis shows that the AP alignment leads to larger heat generation than the P alignment. Therefore, the heat generation in the structure changes dramatically with the relative alignment of the two ferromagnetic layers, which is simi-lar to the GMR effect.